Objective: To find, prepare and identify a new oxyphenisatine di（acetate） analogue. Methods: A suspected derivative of oxyphenisatine di（acetate） was found by high-performance liquid chromatography-quadrupole-time-of-flight-mass spectrometry during the routine screening of weight loss healthcare product. The compound was isolated and purified by column chromatography, and the possible structures were inferred from the information of isotope mass spectra, secondary ion mass spectra, one-dimensional and two-dimensional NMR spectra. Finally, all possible structures were prepared by de novo synthesis strategy, and their fine structures were confirmed by spectral comparison. Results： The compound was identified as 5-Cl oxyphenisatine di（acetate）, a new type of oxyphenisatine di（acetate）, which has not been approved as food additives. Conclusion: The toxicological and pharmacological effects of this compound are not clear and should be of concern to regulators. The mass spectrometric fragmentation rule and the de novo synthesis of doubtful structures of these compounds will be beneficial to confirm the fine structure of new compounds.